Handpiece with water spray



Aug. 25, 1970 N. H. LIEB 3,525,154

HANDPIECE WITH WATER SPRAY Filed April 25, 1 968 4 SheetS -Sheet 1 58 48 50 o mvewron.

NATHANIEL -H. LIEB BY Cauo/v,@bvu, Mal/8am ATTORNEYS.

Aug. 25, 1970 N. H. LIEB HANDPIECE WITH WATER SPRAY 4. Sheets-Sheet 2 Filed April 25, 1968 INVENTOR.

NATHANIEL H. LIEB A TT'ORNEYS.

Aug. 25, 1970 N. H. LIEB 3,525,154

HANDPIECE WITH WATER SPRAY Filed April 25, 1968 4 Sheets-Sheet 3 V w .l

L m H2 me we 15 911 40 INVENTOR.

NATHANIEL H. LIEB BY 1 4 Canon/raw A TTORNEYS.

Aug. 25, 1970 N. H. LIEB HANDPIEQE WITH WATER SPRAY 4 ShetsSheet 4 Filed April 25, 1968 mvewron. NATHANIEL 'H. LIEB &caav

ATTORNEYS.

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United States Patent Oihce 3,525,154 Patented Aug. 25, 1970 3,525,154 HANDPIECE WITH WATER SPRAY Nathaniel H. Lieb, Philadelphia, Pa., assignor to Star Dental Manufacturing Co., Inc. (also known as Star Dental Manufacturing Company, Inc., and Star Dental Mfg. Co., Inc.), Philadelphia, Pa., a corporation of Delaware Filed Apr. 25, 1968, Ser. No. 724,184 Int. Cl. A61c 1/08 U.S. CI. 32-28 Claims ABSTRACT OF THE DISCLOSURE A dental handpiece comprising a hollow body member and a turbine housing at one end thereof. A spray cap is removably secured to the turbine housing and a source of water for the spray cap is internally mounted in the hollow body member. A water spray for a drilled tooth is provided by the spray cap.

This invention relates to a dental handpiece, and more particularly, to a dental handpiece having an integral water spray device provided thereon.

It is known to supply the necessary rotative power to a dental bur by means of a round belt pulley system operatively connected to a source of power. Recently, the demands of high speed dentistry have improved these round belt pulley systems and have provided other systems such as air and water driven turbines to effect dental cutting tool speeds of up to 400,000 rpm.

The use of these high speed systems has resulted in another problem, that of the generation of large amounts of frictional heat in a tooth. It has therefore become necessary to cool the tooth during the drilling thereof. The method of cooling which is used almost exclusively is that of directly supplying a water spray against the tooth while the drilling is being carried out.

Although it has been found that water will elfectively cool the tooth, various problems have arisen with prior art water sprays. In U.S. Pat. No. 3,120,706, owned by the assignee hereof, there is shown an air driven dental handpiece with a water spray which is slidably mounted in order to enable the dentist to position the spray adjacent the bur used for drilling a tooth. The water spray shown in this patent has proved to be completely effective for its intended use. However, there is one problem which has been found with this water spray. When drilling a tooth with a high cusp, it is possible for the cusp to block the spray. Since there is only a single source of spray for the device shown in U.S. Pat. No. 3,120,706, cuspal blockage can effectively prevent a large amount of the coolant water from being delivered to the desired location on the drilled tooth.

An improvement on the device shown in aforementioned U.S. Pat. No. 3,120,706 is shown in U.S. Pat. No. 3,199,196, also owned by the assignee hereof. In the latter patent, the single source for the water spray is replaced by an arcuate, substantially circular water spray tube. The circular water spray tube provides a plurality of sources of water spray around the dental bur. Thus, if one of the ports for the water spray should become blocked by the cusp of a tooth, coolant water will still reach the drilled area from the other ports of the spray device.

The device of this invention is an improvement over the spray device shown in U.S. Pat. No. 3,199,196. In this device, a plurality of ports is providedin a spray head for a dental handpiece. To this extent, the device of this invention enjoys all of the advantages of the device shown in U.S. Pat. No. 3,199,196. However, one of the problems encountered with respect to the device shown in U.S. Pat. No. 3,199,196 was that it was extremely difficult to form a tube into the arcuate, substantially circular shape required for obtaining the plurality of ports for the spray. In this connection, it must be borne in mind that the turbine housing for an air driven dental handpiece is extremely small, and therefore it is extremely diflicult to bend the tubing which would be small enough to be adapted for use with a turbine driven handpiece. Because of this, it has been found that there was a pressure drop for the water spray when the water was forced through the entire circumference of the arcuate spray tube. The resultant elfect was that it was extremely difficult to obtain a uniform spray. Contrasted with this, the spray head of this invention is formed by a machining operation, and therefore the channels carrying the water and air will have a uniform width throughout their entire length. This will result in uniform pressure and a uniform spray volume through all of the ports of the spray head.

Another advantage over the arcuate tube spray device is that the bending of the tubes necessarily resulted in a large diameter for the spray tubes. This was because a small diameter too often resulted in tube blockage during the bending operation. The spray head of this invention which is formed from a machining operation permits the use of Water and air channels of much smaller diameter than those of the bent tubes. This permits greater concentricity of the coolant around the dental bur, and therefore, a smaller volume of coolant water is needed to obtain the desired cooling effect. This in turn results in less chance of gagging by the patient and improved vision for the dentist.

There are devices in the prior art which have a water spray provided in a turbine housing for a turbine driven dental handpiece. However, these devices are formed directly in the housing which is unitary. If the port for the water spray should become clogged, (and cannot readily be cleaned, the entire turbine housing would have to be replaced. Contrasted with this, the spray head of this in vention is readily removable from the end of a turbine housing. Thus, the spray head serves the combined function of an end cap and a means of providing a coolant spray adjacent a rotating dental bur.

If the device of this invention should become clogged, it is readily removable from the dental handpiece and can be cleaned from either the entrance end for the water and air or the exit ports. Additionally, if cleaning becomes too diflicult, the entire spray head can be replaced. This is an important feature to a dentist that finds the spray head has become clogged during use. Thus, it will not be necessary for a dentist to take the time required to clean the spray head while he is operating on a patient. All he will have to do is replace the spray head, which is quickly and easily done, and continue working on the patient.

In another aspect of this invention, the water from the spray cap is delivered through the bur secured in the handpiece. To accomplish this, the bur is provided with a hollow bore which is in fluid communication with the end cap.

It is therefore an object of this invention to provide a dental handpiece with a novel water spray.

It is another object of this invention to provide a novel spray head for use on an air driven dental handpiece.

These and other objects of this invention are accomplished by providing a dental handpiece including a hollow body member and a turbine housing at one end of said hollow body member, said turbine housing including rotary chuck means therein adapted for securing a dental bur, said hollow body member including a conduit adapted to deliver a liquid, a removable cap secured on said turbine housing, said cap being at one end of said 3 turbine housing and adjacent the position wherein a dental bur can be inserted in said rotary chuck, said cap having at least one channel for reception of a liquid, and said cap being releasably connected to said conduit.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a side elevational view, partly in section, ofa first embodiment of the handpiece with water spray of this invention;

FIG. 2 is an enlarged side elevational view, partly in section, of the turbine end of the handpiece of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary sectional view of the spray cap of the device of FIG. 1;

FIG. 5 is a fragmentary side elevational view of the second embodiment of the handpiece with water spray of this invention;

FIG. 6 is an enlarged sectional view of the device shown in FIG. 5;

FIG. 7 is a sectional view taken along the line 77 of FIG. 6;

FIG. 8 is a sectional view taken along the line 8-8 of FIG. 6;

FIG. 9 is a sectional view taken along the line 9-9 of FIG. 6;

FIG. 10 is a fragmentary side elevational view of the third embodiment of the handpiece with water spray of this invention;

FIG. 11 is an enlarged sectional view of the device shown in FIG. 10;

FIG. 12 is a sectional view taken along the line 12--12 of FIG. 11;

FIG. 13 is a fragmentary side elevational view of the fourth embodiment of the handpiece with water spray of this invention;

FIG. 14 is an enlarged side elevational view, partly in section, of the front end of the device shown in FIG. 13;

FIG. 15 is a sectional view taken along the line 1515 of FIG. 14; and

FIG. 16 is an enlarged sectional view taken along the line 16--16 of FIG. 14.

Referring now in greater detail to the various figures of the drawings wherein similar reference characters refer to similar parts, a handpiece with water spray embodying the present invention is shown at 20 in FIG. 1. Device 20 basically comprises an elongated hollow housing 22 having an adaptor nut 24 at one end for connection of water and air tubing. The other end includes a contra-angle extension 26 having a turbine housing 28 on the end thereof.

Turbine housing 28 includes a turbine cartridge comprising upper and lower ball bearings 30 (only the outer race of lower ball bearing 30 is shown in FIG. 2), a rotor shaft 32 having an extension with a hexagonal outer surface 34 and a collet chuck 36 (FIG. 3) having a pair of jaws separated by openings 38.

To the extent described, the handpiece can be the same as that shown in prior U.S. Pats. No. 3,120,706 and No. 3,199,196. Thus, as explained in greater detail in Pat. No. 3,120,706, collet 36 is threadedly secured within rotor shaft 32. Together, the collet and the rotor shaft provide a rotary chuck for a dental bur. The threaded advancement of the collet within the rotor shaft causes a compression of the jaws of the collet, thereby securing a dental 'bur 40 in place. The rotor shaft is held against rotation when the collet is moved through the use of a wrench placed over the hexagonal head 34 or through the use of a finger which passes through the turbine housing 28 into the rotor blades, as shown in U.S. Pat. No. 3,120,706. The collet is then advanced by inserting a square or hexagonal whench into a square or hexagonal hole in the top 4 of the collet and threadedly rotating the collet relative to the internally threaded rotor shaft.

It is to be understood, however, that the specific rotary chuck used with the handpiece is not critical to the invention, and any chucking means known in the art can be used in the handpiece of this invention. For instance, a plastic sleeve collet can be used or a spring loaded collet, such as that shown in U.S. Pat. No. 3,074,167, can be used. One end of turbine housing 28 is closed by removable end cap 42. The other or bottom end is closed "by a removable spray head 44 which serves as an end cap. Cap 44 is internally threaded, as shown at 46, and is threadedly secured on turbine housing 28. End cap 44 includes a pair of coaxial spaced annular grooves 48 and 50. Grooves 48 and 50 can be formed by a machining operation directly on a blank which is formed into cap 44. Alternatively, they can be formed by securing a pair of spaced rings on the upper surface 52 of the end cap.

A tube 54 projects from one side of the end cap 44 and is in fluid communication with groove 48. A second tube 56 projects from the end cap 44 adjacent tube 54 and is in fluid communication with groove 50. A disk 58 is placed over grooves 48 and 50 and eflectively seals the grooves to form closed channels. Disk 58 is also provided with a plurality of holes 64 which are in fluid communication with groove 48. Holes 62 and 64 are aligned, as seen in FIG. 3. Although the holes are shown in FIG. 2 as projecting vertically downward, they can be angled in the direction of bur 40.

A flexible tube 66 is slidably mounted on tube 54 and a flexible tube 68 is slidably mounted on tube 56. Tubes 66 and 68 can be made of any resilient material, such as rubber or plastic. A suitable plastic tube is that sold under the trademark Tygon. Tubes 66 and 68 are in turn connected to rigid metal tubes 70 and 72, respectively (FIG. 2). The metal tubes, in turn, pass into the hollow body 22 of handpiece 20 (FIG. 1) where they are each secured to individual flexible tubes 75. The flexible tubes 75 are in turn secured to rigid conduits within housing 22. The metal tubing 70 and 72, flexible tubes 75 and the rigid conduits are the same as those shown in aforementioned U.S. Pat. No. 3,199,196. Handpiece 20 will also include a rigid tube 76 for furnishing air to rotate the turbine of the handpiece.

The handpiece 20 is used in the normal manner for the drilling of teeth. When the handpiece is actuated, water will pass through tubing in hollow body 22, through tube 70, tube 66 and into groove 48, from which it will :be directed downwardly toward bur 40 through holes 64. Air will pass through the tube in hollow body 22, through tube 72, tube 68 and into groove 50 from which it will pass through holes 62 in the direction of bur 40. Theair serves to atomize the water as the two are mixed. If desired, the air and water channels can be reversed, and therefore water will pass through groove 50 and air will pass through groove 48. Where an excess amount of water is desired, it is possible to pass water through both grooves 48 and 50.

When it is desired to clean or change the spray cap 44, tubes 70 and 72 and their associated flexible tubes 66 and 68 are slid rearwardly in the direction of arrow 74 in FIG. 2. The tubes are readily slidable in this direction because of the flexible tubing 75 within hollow body 22. Thereafter, end cap 44 can be threadedly removed from the turbine housing 28 and cleaning can be accomplished by passing fine wires through tubes 54 and 56 and through openings 62 and 64. The end cap 44 can then be threadedly replaced in turbine housing 28. The tubes 54 and 56 are positioned in the end cap in such a manner that they will be in the position shown in FIGS. 2 and 3 when the end ca 44 is threadedly secured in place.

An important feature of having both end caps 42 and 44 removable is that the turbine cartride comprising the ball bearings, the rotor shaft, the rotor blades and the collet can easily be removed and replaced by the dentist.

If both end caps were not removable, replacement would be more diflicult. Thus, as seen in US. Pat. No. 3,120,706 the replacement of the turbine cartridge is easily accomplished through removal of the two end caps.

A second embodiment of the handpiece of this invention is generally shown at 80 in FIG. 5. Device 80 can be a part of the same handpiece as that shown in FIG. 1 and will include a contra-angle extension 26 with a turbine housing 28 and an upper end cap 42. As seen in FIG. 7, end cap 42 is provided with a central opening 82 for insertion of a wrench to advance collet 36 (FIG. 8). Device 80 also includes upper and lower ball bearings 30, a rotor shaft 32 having a hexagonal end 34 and rotor blades 85. A dental bur 40 is secured by the collet in the same manner as that described for device 20.

In this embodiment an end cap 84 is provided which is secured at the bottom of turbine housing 28 by a pressed fit between the wall 86 of the end cap over a reduced collar 88 at the bottom of the turbine housingIn this embodiment an upper annular grove 90 is formed in the end cap and a lower annular groove 92 is formed in the end cap. A plurality of holes 94 connects groove 90 with the exterior of end cap 84. A plurality of holes 96 connects grove 92 with the exterior of end cap 84. As seen in FIG. 8, holes 94 and 96 are aligned. As seen in FIG. 6, holes 94 are interior of holes 96, and all of the holes are angled inwardly toward bur 40.

As seen in FIG. 7 a tube 98 is in fluid communication with groove 92 and projects upwardly therefrom through the top wall of end cap 84. A second tube 100 is in fluid communication with groove 90 and projects vertically upward through the top of end cap 84. When the end cap is secured in place on the handpiece, tube 98 is telescoped into tube 102 which passes through contra-angle extension 26 and hollow body 22. Likewise, tube 100 is telescoped in liquid tight communication into tube 104 within the hollow body of the handpiece.

The device 80 is used in the. same manner as the device 20. Thus, water will pass through tube 102 into groove 92 and out through openings 96. Air will pass through tube 104 into groove 90 and out through openings 94. If desired, the water and air supply lines can be reversed, or water can be passed through both grooves.

When it is desired to change or clean the end cap 84, it is pulled vertically downward from the turbine housing 28 for removal. After cleaning it is pressed in place with the tubes 98 and 100 being inserted in tubes 102 and 104, respectively. Tubes 102 and 104 can be made from a rigid plastic which is cemented in place. Alternatively, they can be formed from stainless steel and taper joints can be provided for the rapid seating of tubes 98 and 100 in tubes 102 and 104. In either case, a liquid tight seal is obtained.

A third embodiment of this invention is generally shown at 110 in FIG. 10. Device 110 includes all of the details of the other embodiments including the contraangle extension 26, the turbine housing 28 and the upper end cap 42 having a central opening 82. Device 110 is similar to device 80 in that an end cap 112 includes an outer wall 114 which is secured on turbine housing 28 through a pressed fit. An upper groove 116 and a lower groove 118 are provided having angled openings 120 and 122, respectively. In this embodiment, a horizontally extending tube 124 is in fluid communication with annular groove 116 and a horizontally extending tube 126 is in fluid communication with annular groove 118. Tubes 124 and 126 are connected with air and water conduits or tubes in contra-angle extension 26 through the use of flexible tubing 128 and 130, respectively. Tubing 128 and 130 can be rubber or plastic.

The device of embodiment 110 is used in the same manner as the previous embodiments. Thus, air and water can be used in either the upper or lower grooves, or water can be passed through both grooves. As a further modification, of embodiment 110, end cap 112 can be threadedly secured in place instead of using the pressed fit.

A fourth embodiment of this invention is generally shown at in FIG. 13. Device 140 includes all of the details of the other embodiments including hollow housing 22 having contra-angle extension 26 and a turbine housing 28. An end cap 42 is placed on the upper portion of the turbine housing and ball bearings 30 are mounted within the turbine housing. In this embodiment, an end cap 124 is threadedly secured on the bottom of turbine housing 28, as shown at 1 44 in FIG. 14. 'End cap 142 includes an outer substantially cylindrical, but slightly tapered, wall 146 and a horizontal disk 148. Disk 148 includes a central opening 150 through which a dental bur 152 projects.

A water jacket 154 is secured within wall 146 and abuts upper disk 148. Water jacket 154 is preferably formed from a plastic having a low coeflicient of friction, such as Teflon (polytetrafluoroethylene)- or nylon. The water jacket is held in place within wall 146 by any of the means conventionally used for securing plastics to metal, such as crimping or adhesives. Set screws can also be used for obtaining the required securement. Water jacket 154 includes an outer annular channel 156 and an inner anular channel 158. The two grooves are separated by an annular wall 160 but are in fluid communication through the use of one or more holes 162.

A metal conduit 164 projects into groove 156. An O-ring 166 provides a liquid tight connection between conduit 164 and end cap 142. The O-ring is held in place by water jacket 154. Conduit 164 is connected to a flexible rubber or plastic tube 168 which is in turn connected to a rigid tube 170 which enters housing 22. Tube 170' is in turn connected to a flexible tube within housing 22, as is shown and described with respect to the embodiment of this handpiece shown in FIGS. 1 to 4.

Dental bur 152 includes the conventional cutting or abrasive surface 172. However, the bur also includes a central axially extending bore 174 which projects upwardly from the bottom end of the bur. Bur 152 also includes an upper radially extending bore 176 which connects bore 174 with channel 158. Although only one bore 176 is shown, if desired, the number can be increased. The lower end of bur 152 includes three equally spaced radially extending bores 178 (FIG. 16). Bores 178 project inwardly from the exterior of bur 152 and terminate at bore 174..

The use of device 140 is similar to the use of the other handpieces embodying this invention. However, in this embodiment, only a water spray will be used, rather than a mixture of air and water. Thus, water will enter the rear of housing 22, pass through the internal tubing within the housing, leave the housing through tube 170 and enter water jacket 154 through conduit 164. The water within channel 156 will then pass through hole 162 into channel 158. From channel 158 the water will pass through bore 176 and down through bore 174. The water will leave bore 174 axially through the bottom of the bore and radially through holes or ports 178.

One of the advantages of device 140 over the other devices of this invention is that the water will be completely localized in use and will be applied directly to the point where needed. Thus, the purpose of the Water spray is to cool and lubricate the position on the tooth which is being drilled. Since the water used with this embodiment of the invention will pass through the bur doing the drilling, the water automatically is discharged at its intended point of use. For this reason, atomization of the water is not necessary, and therefore, there is no need for an air line to be used in connection with a water line for obtaining the atomization used in the other embodiments. If desired, air can be added to the water used in this embodiment by connecting the air and water lines which are in housing 22 exteriorly of the housing and feeding a mixture of air and water into flexible tube 168. However, the one disadvantage of doing this is that the air and water pressures must be equal to prevent the water from backing up into the air line or the air from backing up into the water line. In view of the difliculty of obtaining these equal pressures, as a matter of convenience, only water will normally be furnished to the bur, without any additional air.

The water jacket 154 is made from a material having a low coeflicient of friction because the jacket must serve the dual function of sealing the water within channel 158 while at the same time permitting the free rotation of bur 152. Teflon is ideally suited for this use.

The number of openings connecting channel 158 with channel 156 and the number of radially extending bores 176 and 178 Within bur 152 can be varied to suit the needs of the user. For most applications, a single opening 162 and a single bore 176 are suflicient. The three bores 178 are advantageous for obtaining uniform distribution of the water within the drilled tooth.

As with the other embodiments, end cap 142 may be secured in place by a pressed fit instead of the threaded connection. An additional advantage of this embodiment is that the bur 152 is internally cooled by the water passing through its central bore.

Although the various embodiments of this invention have been described as being used with air driven turbine handpieces, it is to be understood that the spray caps are adapted for use with any dental handpiece. Additionally, any of the rotary chucking devices known to the art can be used for holding the dental bur 40 or 152 in place.

Without further elaboration, the foregoing will so fully illustrate my invention that others may, by applying current or future knowledge, adopt the same for use under various conditions of service.

What is claimed as the invention is:

1. A dental handpiece including a hollow body member and a turbine housing at one end of said body member, said turbine housing including rotary chuck means therein adapted for securing a dental bur, said hollow body member including a conduit adapted to deliver a liquid, a removable cap secured on said turbine housing, said cap being at one end of said turbine housing and adjacent the position wherein a dental bur can be inserted and held in said rotary chuck, said cap having at least one channel for reception of a liquid, said cap being releasably connected to said conduit, said dental bur being mounted in said rotary chuck and having an axially extending bore, an upper radially extending bore which is in fluid communication with said axially extending bore and the exterior of said bur, and a lower radially extending bore which is in fluid communication with the exterior of said bur and said axially extending bore, said upper radially extending bore being in fluid communication with said channel whereby water entering said channel will pass through said channel into said upper radially extending bore, down through said axially extending bore, and out through said lower radially extending bore, said cap having a circular opening at the center thereof, said bur being mounted in a fluid-tight relationship with respect to said opening, whereby all water within said channel will pass from said channel into said upper radially extending bore, down through said axially extending bore, and out through said radially extending bore, and a portion of said cap contacting said dental bur to form said fluid-tight relationship, said portion comprising a plastic having a low coeflicient of friction.

2. The dental handpiece of claim 1 wherein said plastic comprises polytetrafluoroethylene.

3. The dental handpiece of claim 1 wherein said cap includes two channels which are in fluid communication,

said channels being concentric, with the innermost of said channels being positioned at said opening in said cap and being exposed thereto.

4. The dental handpiece of claim 1 wherein said dental bur includes a plurality of lower radially extending bores with each of said lower bores being in fluid communication with the exterior of said bur and with said axially extending bore.

5. A dental handpiece including a hollow body member and a turbine housing at one end of said body member, said turbine housing including rotary chuck means therein adapted for securing a dental bur, said hollow body member including a first conduit adapted to deliver a liquid and a second conduit adapted to deliver air, a removable cap secured on said turbine housing, said cap being at one end of said turbine housing and adjacent the position wherein a dental bur can be inserted and held in said rotary chuck, said cap having an opening through which said dental bur can be inserted, said cap having two channels formed therein, one of said channels being in fluid communication with said liquid delivery conduit, the other of said channels being in fluid communication with said air delivery conduit, said cap having at least one bore connecting each of said channels, with the exterior of said cap, said bores being adapted to discharge liquid and air from said channels in the direction of said dental bur when said dental bur is mounted within said rotary chuck.

6. The dental handpiece of claim 5 wherein said two channels are concentric.

7. The dental handpiece of claim 5 wherein one of said channels is positioned below the other of said channels.

8. The dental handpiece of claim 5 wherein said cap includes a plurality of bores connecting each of said channels with the exterior of said cap, said bores being adapted to discharge fluid from said channels in the direction of said dental bur when said bur is mounted within said rotary chuck.

9. The dental handpiece of claim 5 wherein said conduits are slidably mounted within said handpiece, and are secured to conduits which are in fluid communication with said channels by flexible tubing.

10. The dental handpiece of claim 5 wherein each of said channels has a conduit in fluid communication therewith, said channel conduits extending exteriorly of said cap, said channel conduits being releasably secured to the conduits of said hollow body member.

11. The dental handpiece of claim 6 wherein said channel conduits extend radially of said cap.

12. The dental handpiece of claim 10 wherein said channel conduits extend axially of said cap.

13. The dental handpiece of claim 5 wherein said cap is secured on said turbine housing by a pressed fit.

14. The dental handpiece of claim 5 wherein said cap is threadedly secured on said turbine housing.

15. The dental handpiece of claim 5 wherein said turbine housing includes a removable end cap on the end opposite said one end.

References Cited UNITED STATES PATENTS 2,442,033 5/1948 Brantly et al. 32-28 3,136,059 6/1964 Nelson 3228 3,256,604 6/1966 Borden 32-28 FOREIGN PATENTS 391,437 4/1933 Great Britain. 932,087 3/ 1948 France.

ROBERT PESHOCK, Primary Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,525,154 Dated August 25 1970 Nathaniel H. Lieb It is certified that errors appear in the above-' identified patent and that said Letters Patent are hereby corrected as shown below:

(1) Column 3, line 75, cancel "whench" and insert therefor -wrench-.

(2) Column 4, line 73, cancel "cartride" and insert therefor -cartridge-.

(3) Column 5, line 20, cancel "grove" and insert therefor -groove-.

(4) Column 6 line 25 cancel "anular" and insert therefor annular--.

(5) Column 6, line 74, cancel "exteriorly" and insert therefor -exteriorally--.

(6) Claim 11, line 1, cancel "6" and insert therefor l0.

M 1w 0! Patent! \ttesting Offioer O 

